This invention relates to centrifugal pumps, and more particularly to centrifugal pumps featuring a construction promoting the removal of debris from a region of a seal chamber which encompasses a shaft driving the impeller of the pump.
In a conventional centrifugal pump, a pump casing includes internal wall structure defining a pump chamber which houses the rotatable impeller of the pump, and to the rear of or in back of this pump chamber a seal chamber, within which a small part of the liquid being pumped (or pumpage) is circulated. A power-driven impeller shaft rotates the impeller during operation of the pump, and this shaft extends to the rear of the impeller and through the seal chamber and thence outwardly through a backplate in the casing. Seal structure encircling this impeller shaft provides a fluid-tight seal between the shaft and the backplate.
In one form of prior art centrifugal pump, a certain amount of the pumpage is circulated in the seal cavity or chamber by the centrifugal action produced by the rotating impeller. The circulated pumpage functions as a coolant for the seal structure sealing the impeller shaft. A problem that arises is that entrained material in the pumpage, such as sand, air bubbles and other debris, tends to accumulate in the seal cavity or chamber in a region directly adjacent the seal structure which seals the impeller shaft to the backplate of the pump casing. The amount of debris and entrained bubbles that so collects can be substantial, and such material interferes with the cooling action and contributes to increased wear in the seal structure. The accumulation of air and/or debris in the region of the seal structure is effected by the manner in which the pump is mounted, with the tendency for air, for instance, to accumulate in the seal structure to be even greater when the pump is in a vertical mode than when the pump is mounted with its impeller shaft disposed horizontally.
This invention concerns a construction for a centrifugal pump which produces a movement in the pumpage or pumped liquid in the seal cavity effective continuously to flush out debris and the like, i.e., entrained air, thus bringing about more efficient cooling and reduced wear in the seal structure.
Another object is to provide a construction producing flushing of debris from a chamber holding pumpage located behind an impeller, which features vane structure joined to the wall defining the chamber producing a flushing action with pumpage moved across the vane structure by the action of the impeller.
A specific object of the invention is to provide a vane construction which includes one or more elongate vane structures extending along the incline of a wall defining a seal chamber in the pump, with the liquid pumped by the impeller moving across the vane structure to produce the circulation pattern desired.
A further specific object of the invention is to provide a vane construction which includes multiple sets of vane segments distributed circumferentially about the wall defining a chamber receiving pumpage fluid.
Yet another object, in one form of the invention, is to provide an improved impeller pump, with a construction for producing flushing of debris from adjacent the seal structure which supports the impeller shaft of the pump, and which further includes a supply for oil or lubricant for lubricating the seal structure.